Work life balance depends on the firm. If you're talking say Virtu or Citadel (two of the best equities players), you have no life, but you're payed a king's ransom. I was single and hungry to be the best technologist possible and it was great before I got married. I worked for Madison Tyler (Virtu's original trading company which finally merged with it for almost 5 years). Others are more amenable to a sensible work/life balance, but it really just depends. DRW and Jump Trading are generally known to have pretty solid work/life balances, but again it just depends on the team and what you do.

The way to break into finance, besides some luck or a recruiter, is being exceptional at what you do. If you write C++, be the best C++ developer you can be. If you tune Linux servers, you better know every sysctl knob literally in and out AND where in the kernel those are actually applied. If the knob doesn't work, perhaps you'll need to write your own (kernel patch) to toggle a specific tcp/ip tunable. I breathe Linux in my sleep because I've always found it fascinating and got lucky when a random recruiter found me while I was working on the Core Systems backend Linux team at Ticketmaster. Then it is simply a matter of putting your resume out and/or finding a recruiter who works with those firms. Some of them are more niche. Jane Street Trading, as an example, requires every employee to write Erlang. Being good at erlang isn't super common so that might be an "in". Two Sigma does a lot of open source work (they have a github and have contributed a lot of stuff to both the Mesos and Kubernetes communities). Honestly man, just do some research, find something you want to learn, and strive to be the best.